1. Field of the Invention
This invention relates to greases used for lubricating bearings in rotating equipment and machinery in automotive, industrial, construction and maritime applications. More particularly, the invention relates to a composition and method for cleaning such bearings and for replacing the bearing lubricant without the need for removing the bearings from service during the cleaning process.
2. Description of Related Art
Recommended procedures for maintaining the bearings used in rotating equipment and industrial machinery typically include two phases: periodic greasing (adding supplemental grease to a bearing), which is done at short-term service intervals as part of the normal lubrication schedule; and grease removal and repacking, which is done at relatively longer service intervals. In the past, grease removal and repacking has most often been done by shutting down the equipment or machinery, removing bearings from their journals, stripping the grease and contaminants from the bearings by hand-brushing with hydrocarbon solvents, and then laboriously repacking fresh grease into the bearings and re-assembling the bearing system. Hydrocarbon solvents pose well-known risks to workers and to the work environment because of their volatility and flammability.
Calcium sulfonate greases are typically available in one of two different types. The simple or uncomplexed form of calcium sulfonate grease was first invented and used in industrial applications in the early 1970's. The complexed calcium sulfonate greases were developed in the early 1980's and brought to market in the middle of that decade. Due to the superior properties of the complexed greases over the simple calcium sulfonate grease, most companies currently involved in calcium sulfonate grease production make the complexed greases. The technology used in producing the greases is described in numerous U.S. and foreign patents including, for example, U.S. Pat. Nos. 4,560,489; 5,126,062; 5,308,514 and 5,338,467. Other prior art compositions, apparatus and methods for flushing and repacking bearings are disclosed, for example, in U.S. Pat. Nos. 2,160,214; 3,717,222; 4,113,059; 4,727,619; 5,080,198; and 5,992,569.
A composition and method for cleaning and repacking bearings are needed, however, that do not require the use of complexed calcium sulfonate greases or of potentially harmful solvents, and that can be easily and efficiently employed during operation of the equipment or machinery, thereby reducing maintenance costs and simultaneously avoiding loss of production during equipment downtime.